Position determination techniques using Satellite Positioning Systems (SPSs) have a large variety of uses in commercial, government and private applications. In navigational applications, such as those in which the user aims to follow a particular trajectory while mobile, it is often desirable that the receiver provide continuous position fixes at a constant rate. These applications typically require that the receiver tracks each available SPS satellite and demodulates the navigation data continuously.
Typically, conventional SPS receivers cannot provide continuous tracking and demodulation under conditions of low received signal levels and/or high signal dynamics in the range and Doppler dimensions. The high signal dynamics may be caused by the relative motion between the satellite and the user device or by the relative frequency drift between the satellite oscillator and user device oscillator. These adverse reception conditions typically require variable processing schemes to optimize performance. However, using conventional hardware solutions, it is difficult or impossible to implement such adaptive processing schemes in real time.